Protecting resin-encapsulated components

Abstract

A method of protecting surface mount capacitors from moisture and oxygen corrosion by applying a thermally curable pre-coat resin to a portion of the terminals of a capacitor and encapsulating the capacitor element(s) with a protective resin. The pre-coat resin is substantially rigid at ambient temperatures and flexible at elevated temperatures and is preferably a lactone-containing epoxy resin. The pre-coat resin may be applied to a solder coating-free portion of the terminals by brush or wiper prior to encapsulating the capacitor element(s) with the protective resin.

1. A method of protecting surface mount capacitors from moisture and oxygen corrosion, the capacitor having at least one capacitor element and terminals connected to the capacitor element, said method comprising the steps of:
 applying a thermally curable pre-coat resin to a portion of the terminals of the capacitor; and  
 encapsulating the capacitor element with a protective resin;  
 wherein the pre-coat resin is substantially rigid at ambient temperatures and flexible at high temperatures.  
 
     
     
       2. A method of protecting surface mount capacitors according to  claim 1  further comprising the step of selecting the pre-coat resin from thermally curable epoxy resins. 
     
     
       3. A method of protecting surface mount capacitors according to  claim 1  further comprising the step of selecting the pre-coat resin from thermally curable lactone-containing epoxy resins. 
     
     
       4. A method of protecting surface mount capacitors according to  claim 1 , wherein said pre-coat resin applying step is performed using a wiper to apply the pre-coat resin onto the portion of the terminals of the capacitor. 
     
     
       5. A method of protecting surface mount capacitors according to  claim 1 , wherein said pre-coat resin applying step is performed using a brush to apply the pre-coat resin onto the portion of the terminals of the capacitor. 
     
     
       6. A method of protecting surface mount capacitors according to  claim 1 , wherein said pre-coat resin applying step is performed using a counter-rotating wheel assembly to apply the pre-coat resin onto the portion of the terminals of the capacitor. 
     
     
       7. A method of protecting surface mount capacitors from moisture and oxygen corrosion, the capacitor having at least one capacitor element, an anode riser wire connecting said capacitor element to an anode terminal and a cathode terminal connected to said cathode capacitor element, said method comprising the steps of:
 applying a thermally curable pre-coat resin to a portion of at least one of said anode terminal or said cathode terminal; and  
 encapsulating the capacitor element with a protective resin;  
 wherein the pre-coat resin is substantially rigid at ambient temperatures and flexible at high temperatures.  
 
     
     
       8. A method of protecting surface mount capacitors according to  claim 7  further comprising the step of selecting the pre-coat resin from thermally curable epoxy resins. 
     
     
       9. A method of protecting surface mount capacitors according to  claim 7  further comprising the step of selecting the pre-coat resin from thermally curable lactone-containing epoxy resins. 
     
     
       10. A method of protecting surface mount capacitors according to  claim 7 , wherein said pre-coat resin applying step is performed using a wiper to apply the pre-coat resin onto the portion of the terminals of the capacitor. 
     
     
       11. A method of protecting surface mount capacitors according to  claim 7 , wherein said pre-coat resin applying step is performed using a brush to apply the pre-coat resin onto the portion of the terminals of the capacitor. 
     
     
       12. A method of protecting surface mount capacitors according to  claim 7 , wherein said pre-coat resin applying step is performed using a counter-rotating wheel assembly to apply the pre-coat resin onto the portion of the terminals of the capacitor.